Over the past few years, our research efforts have been focused on the exploration of novel scaffolds with antimycobacterial activity and eventually to develop new anti-tubercular agents that can improve the current therapeutic regimen as well as effective in the treatment of MDR-TB (Kamal, A.; Babu, A. H.; Ramana, A. V.; Sinha, R.; Yadav, J. S.; Arora, S. K. Bioorg. Med. Chem. Lett. 2005, 15, 1923-1926.; Kamal, A.; Reddy, K. S.; Ahmed, S. K.; Khan, M. N. A.; Sinha, R. K.; Yadav, J. S.; Arora, S. K. Bioorg. Med. Chem. 2006, 14, 650-658.; Kamal, A.; Ahmed, S. K.; Reddy, K. S.; Khan, M. N. A.; Shetti, R. V. C. R. N. C.; Siddhardha, B.; Murthy, U. S. N.; Khan, I. A.; Kumar, M.; Sharma, S.; Ram, A. B. Bioorg. Med. Chem. Lett. 2007, 17, 5419-5422; Kamal, A.; Azeeza, S.; Malik, M. S.; Faazil, S. Int. J. of Medical and Biological Frontiers 2010, 16, 535-568).
Thiolactomycin (TLM) is a thiolactone antibiotic isolated from a soil sample collected in Sayama city, Saitama prefecture, Japan. It is obtained from fermentation broth of Nocardia species, a strain of Actinomycetes (Oishi, H.; Noto, T.; Sasaki, H.; Suzuki, K.; Hayashi, T.; Okazaki, H.; Ando, K.; Sawada, M. J Antibiot. (Tokyo) 1982, 35, 391-395.; Sasaki, H.; Oishi, H.; Hayashi, T.; Noto, T.; Ando, K.; Sawada, M. J. Antibiot. (Tokyo) 1982, 35, 396-400.; Nishida, I.; Kawaguchi, A.; Yamada, M. J. Biol. Chem. 1986, 99, 1447-1454).
TLM exhibits potent in vitro and in vivo activity against many pathogenic bacteria, including Gram-negative and Gram-positive bacteria and M. tuberculosis. It inhibits bacterial and plant type II fatty acid synthases (FAS-II) but not mammalian or yeast type I fatty acid synthases (FAS-I). In Escherichia coli TLM inhibits both β-ketoacyl-ACP synthase I to III and acetyl coenzyme A (CoA): ACP transacylase activities at in vitro and in vivo conditions. However, the above activity is interesting but it is insufficient to warrant further progression of thiolactomycin itself as an anti-TB agent. Therefore, new analogues of thiolactomycin needs to be designed and synthesized that could exhibit potential activity against M. tuberculosis cultures. (Slayden, R. A.; Lee, R. E.; Armour, J. W.; Cooper, A. M.; Orme, I. M.; Brennan, P. J.; Besra, G. S. Antimicrob. Agents Chemother. 1996, 40, 2813-2819.; Noto, T.; Miyakawa, S.; Oishi, H.; Endo, H.; Okazaki, H. J. Antibiot. (Tokyo) 1982, 35, 401-410.; Hayashi, T.; Yamamoto, O.; Sasaki, H.; Kawaguchi, A.; Okazaki, H. Biochem. Biophys. Res. Commun. 1983, 115, 1108-1113.; Tsay, J. T.; Rock, C. O.; Jackowski, S. J. Bacteriology 1992, 174, 508-513).
In this laboratory a number of C-4 analogues of thiolactomycin has been designed, synthesized and evaluated against four different species of M. tuberculosis namely M. tuberculosis H37Rv ATCC 27294, clinical isolates (sensitive and resistant), M. avium ATCC 49601 and M. intracellulare ATCC 13950. Of them some analogues have shown good activity against these strains with a MIC values in the range of 1.0-16 μg/mL (Kamal, A.; Shaik A. A.; Sinha, R.; Yadav, J. S.; Arora, S. K. Bioorg. Med. Chem. Lett. 2005, 15, 1927-1929.; Kamal, A.; Azeeza, S.; Malik, M. S.; Shaik, A. A.; Rao, M. V. J. Pharm. Pharmaceut. Sci. 2008, 11, 56s-80s.; Kamal, A.; Azeeza, S.; Malik, M. S. In Drug resistant tuberculosis: Causes, Diagnosis and Treatments. N'guy, S.; K'ung, Z. Eds.; Nova publishers: New York, 2009). The compounds mentioned in J. Pharm. Pharmaceut. Sci. 11 (2); 56s-80s, 2008 are same as mentioned in the journal Bioorg. Med. Chem. Lett. 2005, 1927-1929 and they have methyl group on piperazine ring system.
Compounds of Bioorg. Med. Chem. Lett. 2005, 1927-1929
1a-fR = Br 2a-f 3a-f 4a-fabcdefn3456810
The results from previous studies encouraged us for the design, synthesis and evaluation of a library of new molecules based on thiolactomycin against sensitive and multi-drug resistant strains, which are presented in the present specification. The compounds of the present invention have quinoline ring system with different substituents on piperazine ring of thiolactone. The introduction of a quinoline ring system to the piperazine ring in the structures of present compounds results in a substantial increase in activity.